1. Field of the Invention
This invention relates to computer systems and, more particularly, to storage systems.
2. Description of the Related Art
Computer systems often process large quantities of information, including application data and executable code configured to process such data. In numerous embodiments, computer systems provide various types of mass storage devices configured to store data, such as magnetic and optical disk drives, tape drives, etc. To provide a regular and systematic interface through which to access their stored data, such storage devices are frequently organized into hierarchies of files by software such as an operating system. Often a file defines a minimum level of data granularity that a user can manipulate within a storage device, although various applications and operating system processes may operate on data within a file at a lower level of granularity than the entire file.
In many conventional file-based computer systems, files may be created, destroyed and manipulated with relatively few constraints. Typically, files may be arbitrarily named, subject to operating system conventions, and often, unlimited numbers of exact copies of existing files may be made with ease, subject only to available storage capacity. While such ease of data proliferation may simplify system operation for the user, it may also result in inefficient use of storage devices. For example, storage devoted to multiple identical copies of a given file may be redundant and therefore wasted. Further, if a user creates multiple copies of a given file, gives each a unique identity, and then proceeds to work with each file individually, the relationships among files (such as their common origin, type, and degree of common content) may be obscured over time. Still further, not all types of files may be equally well suited to a given type of storage available in a system. For example, recently used data files may be more likely to be used again in the future and therefore good candidates to be stored in faster storage such as a disk drive, but files unlikely to be used again may be better suited to be stored on a tape drive.
Attempting to track file operations as they occur, to thereby gather greater information about such operations, is complicated by the problem of how such operations may be detected. In most operating system embodiments, application programs may be isolated from one another during execution such that one application may only detect the effects of another, such as a write to a given file, after the fact. However, at the point a file operation (e.g., a modification or copy operation) is visible to another application, the operation may have already occurred and information regarding the source of the operation may no longer be available.